Modular, Human Blast Overpressure Body Testing Surrogates

Priority is claimed on the following application: Country: Unites States of America, Application No. 63/518,991, Filed: Aug. 11, 2023, the content of which is/are incorporated herein by reference in its entirety.

This invention was made with Government support under Contract No. HT942523C0054 awarded by US Army Medical Research Acquisition Activity. The Government has certain rights in the invention.

1,2 Explosions can cause bodily and nerve system injuries. Traumatic Brain Injury (TBI) and Post-Traumatic Stress Disorder (PTSD) are well-known blast-related injuries. Lung and other internal organ injuries are other types of polytrauma sustained by persons exposed to blast. Thus, evaluating PPE, blast sources, and environments for human blast exposure using surrogates may be needed to mitigate, understand, prevent, and treat blast overpressure injuries and illnesses.

3,4 5-7 3 4 There are only twocommercialized blast-specific dummies or surrogates, and a limited number of research prototypesproviding sensor-integrated blast overpressure data for human subjects. The two commercialized technologies, the Thoracic Surrogateand WIAMan(Warrior Injury Assessment Manikin) are not complete surrogate solutions for evaluating PPE, weapon systems, or blast environments. The Thoracic Surrogate focuses on the thorax or chest for PPE evaluation with a commercial off-the-shelf (COTS) vehicle impact dummy head and neck. Whereas the WIAMan was designed to evaluate occupant injury kinematics during a ground vehicle underbody blast event such as an Improvised Explosive Device (IED) explosion to improve military vehicle blast protection.

The prior art research prototypes have made progress in capturing blast-specific data but are not all-in-one solutions. These prototypes have two major deficiencies, they are not complete surrogates, e.g., are only a head that still needs to be attached to the rest of a costly crash test dummy, and they rely on costly COTS laboratory blast sensors and supporting electronics that need specialized knowledge to operate and process data.

A surrogate for testing and evaluating PPE, weapons systems, and blast environments for human blast exposure must provide accurate high-resolution blast-pressure and/or acceleration data and be a complete, anatomically correct, biofidelic, and easy-to-use solution. Prior art for human blast surrogates does not meet these requirements.

This invention is an anatomically correct, sensor-integrated male and female blast surrogate designed for testing and evaluating personal protective equipment (PPE), weapon systems, and environments for blast protection and exposure. The surrogate enables key measurements of pressure and/or acceleration exposure during blast events at various locations such as the skull, forehead, eyes, ears, in-brain, chest, lungs, belly, and other internal organs. This uniqueness is achieved using metamaterial engineering and three-dimensional (3D) printing techniques to produce a surrogate that mimics human blast response with minimized surrogate tissue layers and complexity.

The surrogate is equipped with sensors capable of capturing high-resolution, high sampling rate, and time-synchronized data from blast events. These sensors can integrate and capture data from additional sensors, including but not limited to acceleration, temperature, and force sensors. The modular design allows for easy and low-cost replacement of damaged parts, upgrades, or alternate modules, enhancing its reusability and customizability. The surrogate is designed to be man-portable, durable, water-resistant, wireless, and battery-powered.

In the preferred embodiment, the sensing elements and conditioning circuitry with standardized connections are connected to the main controller's jacks using standard audio cables and connectors, including but not limited to 4-pole stereo cables. These cables are fed through various channels in the surrogate, allowing for easy replacement and modularity with low noise. The sensors have standardized connector jacks to both the main controller board and sensing element boards, resulting in modular remote sensing boards that can be placed anywhere on or in the surrogate. These replaceable remote sensing element boards are powered by the main controller via two of the poles in the audio cable, with the other two poles used as ground and signal channels.

One aspect of the present invention is a modular anatomically correct male and female surrogate, comprising an anatomical head and torso, with various simulated organs and multiple pressure and/or acceleration sensors, a controller for data processing, and a power supply. The invented surrogate offers capabilities for capturing data at various locations, including in the brain, and provides an anatomically correct human form for testing and evaluating PPE and environments.

According to another aspect of the invention, the surrogate is manufactured using 3D printing techniques, including but not limited to fused deposition modeling (FDM), selective laser sintering (SLS), and stereolithography (SLA) with various materials. The 3D printed construction utilizes metamaterial engineering and/or multi-material construction to match human tissues'acoustic impedance, attenuation, and blast response concerning pressure. This approach allows low-cost production and replication of complex anatomical structures and tissues.

According to another aspect of the invention, the surrogate data from an event can be modified to more closely match human models, simulations, and cadaver reference data utilizing mathematical functions or algorithms to correct or calibrate output test data. According to another aspect of the invention, the surrogate captures multiple channels of high-resolution data while allowing easy replacement of damaged parts and enabling the data to be sent wirelessly via Bluetooth, Wi-Fi, or physical connections to different devices. Alternatively, the sensor control boards can be equipped with other onboard instrumentation, including but not limited to accelerometers, gyroscopes, thermometers, and barometers, to evaluate body kinematics and blast physics during a blast overpressure event.

According to another aspect of the invention, the surrogate is powered by an onboard battery or an external power source. The design makes it man-portable, durable, water-resistant, wireless, and battery-powered.

According to another aspect of the invention, the surrogate is designed to trigger a blast event based on sensor data, offering similar responses to human models and cadaver tests in waveform properties, and providing a rolling buffer to include pre-peak data.

According to another aspect of the invention, the surrogate's head contains an anatomically correct brain cavity designed to accommodate any brain simulant material or system.

According to another aspect of the invention, the surrogate is used for occupational blast injury assessments, collecting blast and acceleration data, replicating personnel positioning during blast events, and robustly supporting free field, enclosed space, and shock tube testing.

According to another aspect of the invention, methods for operating the surrogate include affixing the surrogate or individual components to test stands or to crash test dummy components for flexible and customizable blast testing.

According to another aspect of the invention, the surrogate is manufactured using other manufacturing techniques, including but not limited to injection molding, blow molding, casting, and thermoplastic and thermoform molding.

According to another aspect of the invention, the surrogate's modular design emphasizes the adaptability and flexibility of the system, allowing for easy replacement and customization of damaged or specific parts.

Persons of ordinary skill in the art will realize that the following description is illustrative only and not in any way limiting. Other instances of the invention will readily suggest themselves to such skilled persons.

The present invention is particularly useful for sensing, recording, and storing pressure and acceleration of a blast event experienced at various locations on and in a simulated human body for post-event analysis and evaluation of exposure. The BOB includes multiple pressure sensors and/or acceleration sensors and at least one activation sensor which may be, for example, a multi-axis accelerometer and/or a selected pressure sensor channel, or a plurality of pressure sensor channels. The pressure signals are conditioned and processed with a microcontroller (MCU). The amplitude and time history of sensors and at least one other sensing element to measure a parameter such as pressure and/or other sensor data is used for the calculation of a blast severity metric, such as pressure impulse. The pressure sensors can be made of various materials and/or microelectromechanical systems (MEMS) including, but not limited to, a piezoelectric, piezoresistive, capacitive, diaphragm, or strain-gage-based sensing element(s). The activation sensor may be an accelerometer(s) or may also be made using various material systems and MEMS including, but not limited to, a piezoelectric, piezoresistive, or capacitive type(s).

Power is supplied either by an internal battery or an external power source, ensuring continuous power to all pressure sensors. Output data from all sensors are written into a rolling memory to include pre-peak data. After a blast is sensed, recording is triggered, and data is stored on non-volatile memory including pre-peak data. The recorded blast data can be processed in the MCU or can be downloaded and post-processed after the event to determine the blast exposure severity. The quantitative amplitude of at least one blast parameter can be displayed with an indicator light and/or a digital display, and/or sent wirelessly to a mobile device, desktop computer, or server. The maximum pressure and/or acceleration recorded by any of the sensors (or an average or other mathematical computation of any combination, or all measured pressures), may be displayed, stored, or transmitted.

Processed data is recorded to a blast event memory which can be written to and read via either wired or wireless communication. In some instances of the invention, the blast event memory is co-located within the housing of the surrogate. In other instances of the invention, the blast event memory is located outside of the housing of the surrogate. The power consumption of the surrogate is minimized by utilizing low-power modes on the MCU and powering the pressure sensors only when the surrogate is in use.

The pressure history of all pressure sensors in the BOB and the data history from other blast parameter sensors in the BOB is analyzed and, at a minimum, the peak pressure and pressure impulse from all pressure sensors are calculated. The resultant pressure and directionality of the blast concerning the BOB can be determined with an analysis of the pressure history of each pressure sensor or a combination of sensors.

Metamaterials, specifically related to blast and acoustics, utilize engineered structures to influence the macroscopic properties of a system that are not naturally observed in the underlying materials. These properties include but are not limited to, wave speed, acoustic impedance, and frequency response. The unique construction of these metamaterials allows for the manipulation of how pressure waves propagate through the surrogate, thereby enabling the replication of human tissue system response under blast conditions with respect to the desired measurement location.

In the context of this invention, metamaterial construction involves creating complex structures using advanced 3D printing techniques. These structures can be designed with a reduced number of layers (n1), where n1 is less than the actual number of tissues (n) encountered by a pressure wave in a human system. The design of these layers is tailored to match the resultant system's acoustical properties, including wave speed, acoustic impedance, and attenuation. By carefully engineering the geometrical and material properties of these layers, it is possible to ensure that the measurement at a specific location (X) within the surrogate, after encountering n1 layers, closely matches the measurement at the same location (X) within a human system after encountering n tissues.

10 10 12 26 15 14 28 12 26 16 13 17 21 24 23 13 17 25 24 23 13 17 25 26 33 32 31 26 30 12 29 12 26 29 30 22 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 1 2 3 4 5 FIGS.,,,, and 1 2 3 4 5 FIGS.,,,, and 7 FIG. 7 8 FIGS.and An illustrative instance of the BOBof the present invention is shown in an isometric view in, a front view in, a right-side view in, a left-side view in, and a back-side view in. The BOBis composed of a head with an upper portionattached to the lower portion, connected to a neckwith an adapter, to the torso. As can be seen in, the upperand lowerportions of the BOB head contain removable modular ears,, eye, and nosewith pressure sensors disposed on the forehead, back head, right ear, left eye, and left side of the head. Persons of ordinary skill in the art will appreciate that while the instance of the invention illustrated inincludes five non-in-brain pressure sensors,,,, andon the head, other instances of the invention may contain fewer pressure sensors, a larger number of pressure sensors, or other types of sensors such as acceleration sensors. Also, present in the lower portionBOB head as illustrated inare three additional pressure sensor locations for in-brain pressure measurements located in the front-brain, mid-brain, and rear-brain, other instances of the invention may contain fewer in-brain pressure sensors or a larger number of pressure sensors in the same or different locations. As shown in, the lower portionof the BOB head includes the lower geometry of an anatomically brain cavitywhich attaches to the upper portion of the headwith an anatomically correct upper brain cavity. Once the upperand lower portionof the head are assembled via bolts, glue, or other mechanical fastening means, filling of the combined anatomically correct brain cavity,with any brain simulant material is accomplished with a threaded holethat may be later plugged. Persons of ordinary skill in the art will appreciate that the simulated brain may be added via other means such as installing a completed brain system complete with ventricles, white and grey matter simulants, and suspended in simulated cerebrospinal fluid (CSF).

6 FIG. 6 FIG. 28 46 44 43 19 27 18 19 27 20 19 27 27 As shown inthe BOB torsoconnects to the neck and head assembly with threaded fasteners, but persons of ordinary skill in the art will realize that the neck and/or head may be attached via other means such as with adhesives, interlocking geometry, or other mechanical means. In the illustrative example shown inthere is a channeland voidfor passing wires from the simplified simulated lung system, upper chest pressure sensor, and lower belly pressure sensor, other instances of the invention may contain fewer pressure sensors or a larger number of pressure sensors at various locations. The simplified simulated lung systemillustrated example is a polyurethane (PU) foam ball residing in a circular openingcontaining the same remote sensor in the center used at other non-brain locations such as the upper chest. Persons of ordinary skill in the art will appreciate that while the instance of the PU foam ball simulated lung systemillustrated with a circular opening to the outside atmosphere, instances using other simulated lungs will readily suggest themselves, such as using any simulant lung system (with or without) an openingof any geometry.

9 10 FIGS.and 50 60 47 49 50 46 48 10 As shown in, the remote sensing PCBs for non-in-brainand in-brain measurementshave circuitryfor powering, filtering, and outputting signal from the sensing elementsandvia female audio jacks, with at least one mounting holefor mounting in the invention.

9 10 11 FIGS.,, and 60 50 70 46 46 As shown in, the remote sensing PCBs for in-brainand non-in-brainmeasurements connect to the main controller data acquisition PCBvia standardized female audio connector jacksusing male-to-male cables. Persons of ordinary skill in the art will appreciate that while the instance of the invention illustrated uses female 3.5 mm connector jacks, any standard or custom cabling and connectors providing at least power, ground, and signal lines could be used.

11 FIG. 70 52 53 Referring now to, the main controller data acquisition PCBcontains the necessary circuitry and hardware for triggering, recording, storing event data, and wirelessly communicating the collected data via Bluetooth or Wi-Fi using a wireless integrated System on a Chip (SoC) microcontrollerand via hardware connection with USB-C.

53 52 70 48 53 55 Persons of ordinary skill in the art will appreciate that while the instance of the invention illustrated uses a USB-C portfor wired data transfer and an SoCfor Wi-Fi and Bluetooth, other components and modules for wired data transfer, Wi-Fi, and Bluetooth would readily suggest themselves. The main controller data acquisition PCBalso contains mounting holes, the electronics for charging a battery with the USB-C plugand connects to a battery with a standardized JST battery connector.

70 10 70 46 60 50 46 The main controller data acquisition PCBand the battery can be placed anywhere on or in the inventionin a separate housing or integrated into the invention itself. The illustrative example of the main controller data acquisition PCBis disposed with 5 female audio connectorsfor connection of up to 5 remote sensing boards of any type,, but can contain fewer or more connectorsfor sensor channels.

12 FIG. 10 27 28 10 As shown inthe illustrative instance of the BOBshows the openingto the outside atmosphere of the torsoto be a rectangular cavity. Persons of ordinary skill in the art will appreciate that this opening enables flexibility for alternate instances that readily suggest themselves, such as other simulant lungs, torso organs, ribcage, or ballistic simulant systems for enhancing capability for any test need. Persons of ordinary skill in the art will appreciate that this design intent illustrated here could be of any geometry in any location on the BOBsuch that other organs and systems could be accommodated for any other testing need.

13 14 FIGS.and 10 27 28 19 56 27 10 27 10 As shown in, the illustrative instances of the BOBshow the openingto the outside atmosphere of the torsoto be a rectangular cavity containing an anatomically correct simulated lung systemdisposed behind an anatomically correct ribcage assembly. Persons of ordinary skill in the art will appreciate that this example with openingmay also be closed with muscle and/or skin simulant systems such that the BOBcontains no openingfor testing purposes. Persons of ordinary skill in the art will appreciate intent illustrated here could be of any geometry in any location on the BOBsuch that other organs and systems could be accommodated for any other testing need.

10 57 10 58 59 60 10 61 63 62 64 15 FIG. The operational concept for the BOBis illustrated in. A blast eventoccurs and the BOBcaptures the blast event parameters from multiple organ sensors atand is written to non-volatile memory at. The blast data is exported via wired connection or wireless connection atwhere it can be post-processed to correct data and/or analyzed to report key metrics via a BOBsoftware. The post-processed data can be used by the user atas surrogate human data, or used in an injury risk modelto output human blast injury risk for the event at.